Magnetic annunciator or signal device for control panels

ABSTRACT

A miniature annunciator to be mounted on a control panel for determining the status of circuit conditions, remote machine operation, and general supervision has a housing in which is mounted a field reversible coil having at its each end a laterally extending pole piece. Pivoted within such housing on a shaft which extends outwardly from such housing is a permanently magnetized rotor. The axis of the shaft is located centrally between the two pole pieces and is approximately perpendicular to the flux path between the two pole pieces. The housing is provided with a flange by which it is held to the back of the control panel with the shaft extending through the panel. When the polarity of the coil is reversed, the rotor will be angularly moved approximately 90* from a position at one stop to a position at a second stop. The energizing of the coil is done by pulses and when the coil is de-energized, the permanent magnetism in the rotor will help keep it in the position attained by the energization of the coil. That part of the shaft protruding from the face of the panel is provided with a visible member, such as a bar, which is moved from a generally horizontal to a generally vertical position to indicate the condition of circuitry which is also variable on the face of the panel.

United States Patent Juhnke June 25, 1974 MAGNETIC ANNUNCIATOR OR SIGNAL DEVICE FOR CONTROL PANELS [76] Inventor: Paul B. Juhnke, Rt. No. 2, East Troy, Wis. 53120 [22] Filed: Feb. 12, 1973 [21] App]. No.: 331,951

[56] References Cited UNITED STATES PATENTS 3/1954 Lamb 340/373 X 3/1962 Holdway 340/378 X Primary Examiner-George Harris Attorney, Agent, or FirmMichael, Best & Friedrich [57] ABSTRACT A miniature annunciator to be mounted on a control panel for determining the status of circuit conditions,

remote machine operation, and general supervision has a housing in which is mounted a field reversible coil having at its each end a laterally extending pole piece. Pivoted within such housing on a shaft which extends outwardly from such housing is a permanently magnetized rotor. The axis of the shaft is located centrally between the two pole pieces and is approximately perpendicular to the flux path between the two pole pieces. The housing is provided with a flange by which it is held to the back of the control panel with the shaft extending through the panel. When the polarity of the coil is reversed, the rotor will be angularly moved approximately 90 from a position at one stop to a position at a second stop. The energizing of the coil is done by pulses and when the coil is deenergized, the permanent magnetism in the rotor will help keep it in the position attained by the energization of the coil. That part of the shaft protruding from the face of the panel is provided with a visible member, such as a bar, which is moved from a generally horizontal to a generally vertical position to indicate the condition of circuitry which is also variable on the face of the panel.

3 Claims, 5 Drawing Figures MAGNETIC ANNUNCIATOR OR SIGNAL DEVICE FOR CONTROL PANELS BACKGROUND OF THE INVENTION 1. Field of Invention This invention relates to improvements in small inexpensive light weight annuciators adapted to be mounted on a control panel and operated by electric pulses in a monitoring circuit.

2. Description of the Prior Art The most pertinent prior art uncovered in a patentability search are the following US. Pat. Nos: 2,740,955; 2,740,956; 2,283,427; 3,295,238; 3,303,494; 3,311,859; 3,365,824; 3,444,551; 3,451,055; 3,469,258; and 3,537,197. All of these patents show magnetic annuciators for various uses. Many show the axis of rotation as being generally perpendicular to the axis of thepath of the flux from one and only of the pole pieces. At least five of such patents show the path of the flux extending between two pole pieces.

None of the foregoing patents show or teach the permanent magnetic rotor being mounted on a shaft which has a portion extending out through the housing for the coil and rotor. Also, none of them show a visible member carried by the extending part of the shaft which is moved from a substantially horizontal position to a substantially vertical position.

BRIEF DESCRIPTION OF THE DRAWING IN THE DRAWING FIG. 1 is a fragmentary view in perspective of the annuciator embodying this invention mounted on the back of a control panel with the indicating bar visible on the front of such panel;

FIG. 2 is a view in front side elevation of the annunciator with the cover removed to show the limit stops and the relative positioning of the permanently magnetized rotor with respect to the pole pieces;

FIG. 3 is an exploded view of the housing, field reversible coil, pole pieces, shaft with permanent magnetized rotor, cover, and visible position indicating bar;

FIG. 4 is a schematic view of the reversible field core and the relative pole positions assumed at the end of a DC pulse applied in one direction; and

FIG. 5 is a schematic view of the reversible field core and the relative pole positions assumed at the end of a DC pulse applied in the opposite direction.

DESCRIPTION OF THE PREFERRED EMBODIMENT The miniature annunciator shown in the drawing is mounted with other similar annunicators on the back of a control panel of well known construction used by utilities to indicate to control personnel the condition of various transfer circuits, either electrical or other type.

The housing 12 of the annunciator, preferably a molded plastic part, has an interior pocket 14 shaped as shown in FIGS. 2 and 3. The bottom or rear wall 16 has an opening 18 which forms the inner bearing for the enlarged end 20 of a shaft. From the side walls of such pocket, there extend inwardly projections 22 which act as positioning members for the coil and pole piece assembly.- From the bottom 16 there projects forwardly a pair of pins 24 positioned as shown in FIG. 2

which cooperate with a lateral extension on the shaft to limit the rotation of the shaft and provide stops for each end of the rotation travel. The housing 12 also has laterally extending flanges 26 at the sides thereof. The faces of these flanges seat flush against the back of the control panel 10 and fastening pins or other fastening devices (not shown) secure the housing to the panel.

A reversible field coil 28 has extending radially from each end thereof a pole piece 30 which is shaped as shown in FIGS. 2 and 3. The assembly of coil 28 and pole pieces 30 with wire leads 32 is placed within the pocket 14 with a sufficient frictional fit to maintain the combination in the position shown. The outer ends of the pole pieces are turned inwardly to confine the mag net field which during a DC pulse extends from one to the other pole piece and concentrates the path of such field perpendicular to the axis of rotation of the shaft 34.

The shaft 34, as previously described, has an enlarged end 20 which is rotatively fitted in the opening 18 to form an inner bearing. Adjacent to the end 20 the shaft 30 has a larger diameter portion 36 the shoulder of which forms a thrust bearing for the shaft 34. Projecting radially from the portion 36 is a pin-like extension 38. As the shaft 34 is rotated this extension engages one or the other of the pins 24 to limit the extend of rotation of the shaft 34 to about Press fitted on the shaft 34 is a rotor 40 in the form of a disc of alnico alloy or other material permanently magnetized to have diametrically opposite poles as shown in FIGS. 4 and 5. When the shaft 34 and its assembled parts are mounted within the pocket 14, a plastic cover 42 is secured over each pocket. This cover has an opening 44 through which the extended end of the shaft 34 projects. The fit between the opening 42 and the shaft constitutes the outer bearing for such shaft.

The housing with its extended shaft 34 is now positioned on the back of the control panel 10 with the shaft 34 extending through a selected one of the openings in such panel. After the unit is secured to the panel a visible bar 46 is fastened on to the end of the shaft 34 and is rotated in one direction, say counterclockwise, until the shaft is stopped by the engagement between the pin 38 and the right hand pin 24 as viewed in FIG. 2. The bar is continued to be moved relative to the shaft until it is in a substantially horizontal position as shown in FIG. 1. A lock nut 48 is then tightened to fixedly secure the bar on the shaft so that it will rotate with the shaft. In this horizontal positionof the bar the poles of the permanently magnetized rotor are aligned with the poles of the pole pieces 30 as shown in FIG. 4. This position will be maintained after the collapse of the DC pulse which created the field direction shown in FIG. 4 until a reverse direction DC pulse reverses the direction of the field between such pole piece as shown in FIG. 5. The field direction will cause the rotor to rotate clockwise to the position shown in FIG. 5 with the pin 38 abutting against the left pin 24 and with the bar 46 in a substantially vertical position. Either of the positions will be maintained after the collapse of the DC pulse by the permanent magnetism in the rotor as related to the residual magnetism in the poles 30.

The control circuits for energizing, de-energizing and reversing the polarity of the coil 28 and its pole pieces 30 are well known to those skilled in this art and a description will not be presented. Typical control circuits are diagramed in the public literature identified as Switchcraft Engineering Bulletin E839, published by Switchcraft Inc., Chicago, Ill.

In this embodiment the horizontal position of the bar 46 will indicate to the observer a closed circuit and the vertical position an open circuit.

1 claim:

1. A magnetic annunciator adapted to be mounted on a control panel comprising:

a. a housing having an interior pocket with inwardly extending projections and a face for flatly resting on a side of the control panel;

b. a field reversible coil mounted on said housing and having radially extending pole pieces, said coil and pole pieces assembly frictionally fitted in said pocket;

0. a shaft pivoted in said housing, having a permanently magnetized disc-like rotor thereon in the flux path between and continuingly radially spaced from said pole pieces, said rotor having diametrically positioned oppositely magnetized poles, said shaft having a portion extending exteriorly of said housing;

d. stop means in said pocket limiting the angular swing of said shaft to stop said rotor with the poles on said rotor aligned with the poles on said pole pieces in one position upon D.C. pulse in one direction and with the poles on said rotor at approximately a angle with respect to the poles on said pole pieces when said coil is subjected to a DC. pulse in an opposite direction, both of such positions being maintained after collapse of the respective D.C. pulses; and

e. a visible member carried by said portion to indicate the position of said magnetized rotor with respect to said pole pieces.

2. A magnetic annuciator as defined in claim 1 wherein:

said visible member is positioned exteriorly of the control panel. 3. A magnetic annunciator as defined in claim 2 wherein:

said visible member is a bar which has a horizontal position to indicate a closed circuit condition and a vertical position to indicate an open circuit condition. 

1. A magnetic annunciator adapted to be mounted on a control panel comprising: a. a housing having an interior pocket with inwardly extending projections and a face for flatly resting on a side of the control panel; b. a field reversible coil mounted on said housing and having radially extending pole pieces, said coil and pole pieces assembly frictionally fitted in said pocket; c. a shaft pivoted in said housing, having a permanently magnetized disc-like rotor thereon in the flux path between and continuingly radially spaced from said pole pieces, said rotor having diametrically positioned oppositely magnetized poles, said shaft having a portion extending exteriorly of said housing; d. stop means in said pocket limiting the angular swing of said shaft to stop said rotor with the poles on said rotor aligned with the poles on said pole pieces in one position upon D.C. pulse in one direction and with the poles on said rotor at approximately a 90* angle with respect to the poles on said pole pieces when said coil is subjected to a D.C. pulse in an opposite direction, both of such positions being maintained after collapse of the respective D.C. pulses; and e. a visible member carried by said portion to indicate the position of said magnetized rotor with respect to said pole pieces.
 2. A magnetic annuciator as defined in claim 1 wherein: said visible member is positioned exteriorly of the control panel.
 3. A magnetic annunciator as defined in claim 2 wherein: said visible member is a bar which has a horizontal position to indicate a closed circuit condition and a vertical position to indicate an open circuit condition. 